Underwater hydro turbines for generating electrical power from water flows are known in the art. In particular, underwater hydro turbines have been devised for use in unidirectional and bidirectional water flow applications, such as in river and ocean currents and tidal water flows. Due to the increased demand for sustainable power generation, and the desire to reduce the costs of sustainable power generation towards prices of conventional non-sustainable power sources, there is a desire to improve the efficiency and performance of underwater hydro turbine generators, and to reduce their capital, operating and maintenance costs.
U.S. Pat. No. 7,471,009 to Davis et al. discloses a bidirectional hydro turbine generator for generating electrical power from a water flow. The Davis reference discloses a cylindrical housing or duct around the turbine, which accepted water flow from either end, and included symmetrical hydrofoil turbine blades. The Davis reference also discloses a hydro turbine with a dual-sided axial-flux magnetic generator adapted for use in bidirectional fluid flow applications. Certain disclosed embodiments also include guide vanes located on both sides of the turbine to direct water flow onto the turbine blades in bidirectional fluid flow applications.
U.S. Pat. No. 4,025,220 to Thompson discloses a unidirectional hydro turbine for generating electrical power from water flow. The Thompson reference discloses an axial flow unidirectional turbine enclosed within a rigid venturi nozzle and including a flexible fabric flow collector duct extending upstream of the turbine to attempt to capture water flow in a funnel shaped collector duct arrangement.
European Patent Application Publication No. EP 2112370A1 to Spooner et al. discloses a hydro turbine generator for generating electrical power from water flow including at least one set of passive magnetic bearings. In the Spooner reference, one or more sets of passive magnetic bearings are used to support the generator turbine through the repulsion or attraction of opposite pairs of passive magnets, which are separate from the turbine electrical generator components.
The current technology for hydro turbine generators is unsatisfactory for providing a unidirectional hydro turbine generator design which is advantageously configured for efficient and cost-effective electrical generation in unidirectional fluid flow environments, such as river or ocean currents. There is a need therefore for a unidirectional hydro turbine generator which provides improved efficiency and performance of the turbine and generator components, for improved reliability and longevity in aggressive and/or corrosive submerged operating environments, or for reduced complexity and cost of manufacture, operation or maintenance.